DMA (Direct Memory Access) method for supporting high-determinacy network message receiving by TSN (Transport Sensor Network) end system

Abstract

The invention discloses a DMA (Direct Memory Access) method for supporting high-determinacy network message receiving by a TSN (Transmit Sensor Network) end system. The method comprises the following steps of: S1, configuring a submission control table and an address information table; S2, judging whether a time sensitive message is received or not, and if so, skipping to S3; otherwise, skipping to S4; S3, taking out a corresponding message buffer area address, writing the message into a buffer area of a main memory through DMA (Direct Memory Access), traversing a submission control table, finding a first target table item conforming to a current stream id (Identity), and updating a ready state; S4, calculating a difference value between the global time and the starting time of the scheduling period, judging whether the difference value is equal to a submission offset moment or not, and skipping to S5 if the difference value is equal to the submission offset moment and is in a ready state; and S5, taking out the corresponding descriptor address, notifying the DMA to submit the corresponding descriptor, and updating the ready state of the corresponding table item. According to the invention, the jitter of message receiving can be reduced, and the delay certainty of message receiving is improved, so that the end-to-end certainty of the message is improved.

Description

technical field [0001] The present invention relates to the technical field of DMA (DirectMemory Access, direct memory access) in Time Sensitive Networking (Time Sensitive Networking, TSN), in particular to a DMA method used for a TSN end system to support highly deterministic network message reception. Background technique [0002] In industrial control, automatic driving, smart grid and other application scenarios, there is a type of periodic real-time traffic with strict requirements on delay and jitter, which is time-sensitive traffic, and packets belonging to time-sensitive traffic are time-sensitive packets . In some applications, time-sensitive flow also imposes strict requirements on end-to-end determinism. For example, time-sensitive flow in automatic driving system requires end-to-end delay between 100 microseconds and 250 microseconds, and end-to-end jitter between 100 and 250 microseconds. Tens of microseconds or less, where end-to-end determinism means that the...

AI Technical Summary

Problems solved by technology

[0009] However, the working process of the above-mentioned standard DMA engine is "event-triggered", that is, when the number of messages written by the DMA engine to the memory reaches a preset threshold, or when the two events of the receive interrupt timer expire, the DMA The engine will write back the descriptor, that is, submit the message to the driver, and send an interrupt to notify the CPU to process the next message. However, the arrival and occurrence time of these two events cannot be determined. The size of the file may affect the determinism of the message, that is, the standard DMA engine on the network card of the end system does not have the capability of deterministic message transmission

Images